Combustor

A combustor comprising:

• a combustion liner having a cylindrical side wall that defines a combustion chamber inside thereof;
• a main burner positioned at an inlet end of the combustion liner for injecting a pre-mix gas as a flow swirling about a longitudinal axis of the combustor in an annular shape into the combustion chamber to thereby form a reverse flow region at a location downstream with respect to flow of the pre-mix gas, in which at least a portion of the flow of the pre-mix gas flows in an upstream direction from a downstream location within the combustion chamber towards the inlet end of the combustion chamber along a longitudinal axis of the combustion chamber;
• and
• a pilot burner arranged at the inlet end for injecting a pre-mix gas of fuel and air in a single direction confronting the portion of the flow of the pre-mix gas flowing in the upstream direction within the combustion chamber;
• wherein the pilot burner injects the pre-mix gas at an initial velocity higher than a velocity of propagation of flame so as to form a flame holding region, at which the velocity of flow of the pre-mix gas is reduced down to a value equal to the velocity of propagation of flame, at a location spaced from the pilot burner in a direction axially of the pilot burner, and
• wherein the pilot burner includes a pilot nozzle formed in a most downstream end thereof and having an inner peripheral wall flaring axially outwardly in a direction downstream thereof, and a porous member, provided at an upstream end portion of the pilot nozzle, in the shape of a plate having a multiplicity of pores defined therein and is operable to inject the pre-mix gas of fuel and air through the porous member.